/*
 * Created on Jan 9, 2014
 * Created by Paul Gardner
 * 
 * Copyright 2014 Azureus Software, Inc.  All rights reserved.
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License only.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
 */

package org.gudy.azureus2.core3.util;

import java.util.Collections;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import java.util.concurrent.ConcurrentHashMap;

public class ConcurrentHashMapWrapper<S, T> {
    /**
     * ConcurrentHashMap doesn't support null keys or values so this is a hack to support them
     */

    private static final Object NULL = new Object();

    private final S S_NULL = (S) NULL;
    private final T T_NULL = (T) NULL;

    private final ConcurrentHashMap<S, T> map;

    public ConcurrentHashMapWrapper(int initialCapacity) {
        map = new ConcurrentHashMap<S, T>(initialCapacity);
    }

    public ConcurrentHashMapWrapper(int initialCapacity, float loadFactor, int concurrencyLevel) {
        map = new ConcurrentHashMap<S, T>(initialCapacity, loadFactor, concurrencyLevel);
    }

    public ConcurrentHashMapWrapper() {
        map = new ConcurrentHashMap<S, T>();
    }

    public ConcurrentHashMapWrapper(Map<S, T> init_map) {
        map = new ConcurrentHashMap<S, T>(init_map.size());

        putAll(init_map);
    }

    public void putAll(Map<S, T> from_map) {
        for (Map.Entry<S, T> entry : from_map.entrySet()) {

            S key = entry.getKey();
            T value = entry.getValue();

            if (key == null) {

                key = S_NULL;
            }

            if (value == null) {

                value = T_NULL;
            }

            map.put(key, value);
        }
    }

    public T put(S key, T value) {
        if (key == null) {

            key = S_NULL;
        }

        if (value == null) {

            value = T_NULL;
        }

        T result = map.put(key, value);

        if (result == T_NULL) {

            return (null);

        } else {

            return (result);
        }
    }

    public T get(S key) {
        if (key == null) {

            key = S_NULL;
        }

        T result = map.get(key);

        if (result == T_NULL) {

            return (null);

        } else {

            return (result);
        }
    }

    public T remove(S key) {
        if (key == null) {

            key = S_NULL;
        }

        T result = map.remove(key);

        if (result == T_NULL) {

            return (null);

        } else {

            return (result);
        }
    }

    public boolean containsKey(S key) {
        if (key == null) {

            key = S_NULL;
        }

        return (map.containsKey(key));
    }

    /**
     * NOT MODIFIABLE
     * 
     * @return
     */
    public Set<S> keySet() {
        Set<S> result = map.keySet();

        if (result.contains(S_NULL)) {

            result.remove(S_NULL);

            result.add(null);
        }

        return (Collections.unmodifiableSet(result));
    }

    /**
     * Helper for config writing
     * 
     * @return
     */

    public TreeMap<S, T> toTreeMap() {
        TreeMap<S, T> result = new TreeMap<S, T>();

        for (Map.Entry<S, T> entry : map.entrySet()) {

            S key = entry.getKey();
            T value = entry.getValue();

            if (key == S_NULL) {

                key = null;
            }

            if (value == T_NULL) {

                value = null;
            }

            result.put(key, value);
        }

        return (result);
    }
}
